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The present invention relates to the field of automatic test equipment for testing electronic signals generated by equipment under test including complex video signals. More particularly, the present invention relates to software methods (algorithms) for determining the validity of an electrical signal and software methods for analyzing the image content of generic video signals.
Automatic test equipment for the testing and measuring of electronic signals and electronic video signals is known. Frequently, the measuring and analytical capabilities of available test instrumentation are limited to a small subset of basic analysis methods. Furthermore, the cost of building extended functionality into a hardware test unit is often very high and prohibits usage within small to mid-budgeted systems. Included within the cost of this extended functionality is often an inferior duplication of the processing and computational hardware already available within the host system (host computer).
While automatic test equipment for video signals is known, the capabilities are mainly limited to standard video format frame capture and minimal image interrogation due to the computational demand of advanced analysis. The means for visualizing complex, multiple format video images and analyzing their image content are currently beyond the capabilities of typical automatic test instrumentation.
If the analysis capabilities were separated from the hardware test instrumentation and made available as a generic software apparatus, the overall cost of such analysis would be greatly diminished and the application of other existing basic hardware test instrumentation (such as simple analog digitizers) would be increased. With the analysis functionality now residing on the host computer, it is possible to add additional facilities only available because of the capabilities of the host computer""s operating system. The operator gains the ability to interactively perform complex data manipulation and receive dramatic visualization presentation of the results on the station monitor or in hardcopy form. Also important is the opportunity to automate the desired data manipulation and measurements.
It is an object of the present invention to provide a single equipment package and software analysis application capable of handling electrical signals, video signals and audio signals, each in its corresponding environment.
It is another object of the present invention to provide new automatic test equipment and methods for testing electronic signals generated by equipment under test including complex video signals.
Another object of the present invention is to provide new methods including software methods (algorithms) for determining the validity of an electrical signal.
Yet another object of the present invention is to provide new methods including software methods for analyzing the image content of generic video signals.
In order to achieve these objects and others, the invention is a virtual spectrum analyzer (listed as xe2x80x9cVSAxe2x80x9d henceforth) which is a computer software program intended for use with, but not limited to, automatic test equipment. The VSA performs generic software electrical signal analysis by manual interaction or by programming for autonomous operation within an automated testing environment. While analysis methods, such as histograms and FFT calculations are known, the collection of all these methods, combined with a) both manual and automated interfaces, b) enhanced interactive features, and/or c) a video analysis system featuring a xe2x80x9cwindow-within-a-windowxe2x80x9d analysis method is not known.
One of the unique features that the VSA provides is the ability to appropriately handle the test waveform in its proper environment. Normal (digitized) electrical signals will be plotted and displayed much like on an oscilloscope. Digitized audio signals may be presented as audio utilizing the host computer""s sound card and speakers. Digitized video signals may be reconstructed and presented optically as the original image with controls to zoom, invert and manipulate colors. Optical measurements are calculated on a unique window-within-a-window region of interest, which updates themselves automatically anytime any control is modified.
The xe2x80x9cVSAxe2x80x9d encompasses all the methods discussed hereinafter. The VSA comprises five major elements, as follows:
1) Graphical User Interface (listed as xe2x80x9cGUIxe2x80x9d hereinafter);
2) Automated Programmatic Interface (xe2x80x9cAPIxe2x80x9d)/External Interface Module (xe2x80x9cEIMxe2x80x9d);
3) Control Event Handler (xe2x80x9cCEHxe2x80x9d);
4) Data Visualization Engine (xe2x80x9cDVExe2x80x9d); and
5) Toolkit Engine (xe2x80x9cTExe2x80x9d).
Each of these elements will be discussed below.
A significant advantage of the VSA, while not necessarily the uniqueness of all of its components, is the combination of them and the extremely flexible methods to access them. All controls and requests are accessible from a higher level language (programmed through API calls) or directly through the GUI interface (point and click-no programming at all). This provides the ability to design and debug a test, then successfully automate it, all with the same package.
In one embodiment of the method for analyzing and testing a waveform, either an electrical signal, a digitized audio signal or a digitized video signal, a single equipment package is provided including a computer having at least a sound card, at least one speaker and a screen. As noted above, the VSA provides the ability to analyze each waveform in its proper environment. Thus, when the waveform is an electrical signal, a swath of the electrical signal is plotted and displayed on the screen. When the waveform is a digitized audio signal, the audio signal is passed to the sound card and speaker, which convert it to sound. When the waveform is a digitized video signal, the video signal is reconstructed on the screen. Software tools are provided operative on the electrical signal, the audio signal and the video signal to effect changes in the electrical signal, the audio signal and the video signal. When the waveform is the electrical signal or video signal, the changed signal is displayed on the screen. When the waveform is the audio signal, the changed audio signal is directed to the sound card and speaker, the changed signal is thereby heard.
The tools may be controlled via a user interface to enable manual adjustment of the waveform or from a command log generated through programming to perform desired control of the tools. In the latter case, the command log is operatively accessed to obtain the desired control commands for the tools such that automatic adjustment of the waveform via the tools is accomplished.
When the waveform is an electrical signal or a video signal, operability of the tools can be limited to only a selected portion of the electrical signal or video signal on the screen. This selected portion can be displayed in a different area of the screen. By linking the portion of the signal and the entire signal, changes to one will appear on the other.
In another embodiment of the method for performing electrical signal analysis, at least one test signal, e.g., a video signal, is displayed, both manual and automatic manipulation of the test signal(s) is enabled and the manipulated test signal(s) is/are displayed. Data from the manipulation of each test signal may be obtained. The test signals may be obtained by digitizing electronic analog signals from an instrument and optionally storing the digitized signals in a binary file. In the alternative, the test signal(s) may be obtained in a binary file with decimal values, or a single capture of waveform data performed to obtain the test signal therefrom. If multiple captures of waveform data are performed, the captured data may be arranged as a two-dimensional matrix which constitutes the test signal. Additional information about the test signal may be encoded. If the test signal comprises three test signals, all three of the test signals can be displayed on a single screen.
To enable manual and automatic manipulation of the test signal, available options are presented on a screen, and manual selection and adjustment of the available options are enabled through a user interface, e.g., a keyboard or mouse. The available options include plotting options such as time domain plotting, FFT results, spectrum/magnitude plotting, autocorrelation plotting and cross correlation plotting. Also, configuration adjustment options include orientation adjustment of a graph of the test signal, color adjustments, test adjustments, highlighting, and axis scale lock adjustments. Signal manipulation options include filters, a ranking of peaks in the test signal by amplitude, averaging, fixed voltage removal, and addition and subtraction of an additional test signal to the test signal. One or more discrete portions of the test signal may be selected for manipulation, e.g., by determining a boundary of the test signal to define the selected portion, and displaying the selected portion of the test signal in a different area of the same screen as the test signal is being displayed. This enables only the selected portion of the test signal to be manipulated and/or compared to a surrounding portion of the test signal.
In another embodiment, to enable manual and automatic manipulation of the test signal, available options for manipulation of the test signal are created and a library of stored subroutines provided in a memory space to perform the options such that the test signal is able to be manipulated by the running of the subroutines. In this connection, a computer may be programmed to receive the test signal, perform at least one of the subroutines to manipulate the test signal and display the manipulated test signal.
A plot tracking option is also provided and is useful when a portion of the test signal is displayed separate from the display of the entire at least one test signal, although they may both be on the same screen. One or more signal modification techniques are applied either to the portion of the test signal or the entire test signal, and by linking the display of the entire test signal to the display of the portion of the test signal, the application of the signal modification technique(s) to the portion of the test signal or the entire test signal is reflected in the display of the other.